Contrails Over the United Kingdom and France

Contrails (short for “condensation trails”) or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets or, if the air is cold enough, tiny ice crystals. Here, many such contrails can be observed in the airspace over the United Kingdom and France.

Depending on atmospheric conditions, contrails may be visible for only a few seconds or minutes, or may persist for many hours, which may affect climate. Contrails tend to last longer if there is higher moisture in the atmosphere and associated higher level clouds such as cirrus, cirrostratus and cirrocumulus already present before the plane flies through.